Ch. 12 Flashcards
A nerve is a bundle of __________ plus associated connective tissue and blood vessels that lies outside the brain and spinal cord.
Axons.
A ______________________ is any change in the environment that is strong enough to initiate an action potential. An action potential is an _____________________ signal that propagates along the surface of the membrane of a neuron
Stimulus.
Electrochemical.
Arrange these terms in order of information flow for a neuron: axon terminal, dendrite, cell body, axon.
Dendrite -> Cell Body -> Axon -> Axon Terminal
Distinguish between the direction a nerve impulse is carried relative to the CNS for a sensory (or afferent) neuron and a motor(or efferent) neuron.
Afferent: —> CNS
Efferent: <— CNS
Axons in the CNS display little regrowth after injury, unlike axons in the PNS. Provide two reasons researchers have suggested for this lack of regrowth potential for axons in the CNS.
PNS has Schwann Cells that produce Myelin, retaining ability to regenerate axons/nerves.
Oligodendrocytes produce anti-growth factors (Cell Generation).
What specifically accounts for the white color of white matter and the grey color of grey matter
White color of White Matter = Myelin
Grey color of Grey Matter = Nissl Bodies
Which division of PNS would be responsible for sending signals to the motor neurons responsible for skeletal muscle movements?
SNS
Which division of PNS would be responsible for governing contractions of the GI Tract?
ENS
Which of either, Sympathetic or Parasympathetic, is considered the “fight-or-flight” nervous division and which is considered the “rest-and-digest” division?
Sympathetic: Fight/Flight
Parasympathetic: Rest/Digest
What does the negative sign in front of the -70mV tell you about the charge states of the cell membranes?
Inside is more negative than outside for the resting membrane neurons.
The actual number of K+ protein channels called “leakage channels” (i.e. they allow the passive movement or ‘leakage’ of ions down their concentration gradients) versus the actual number of Na+ ion leakage channels favor the movement of K+ ion ____ the neuron and slow the movement of Na+ ions _____ the neuron.
Out of.
Into.
An _______________________ potential , or (nerve) impulse, is a sequence of rapidly occurring events that decrease and reverse the membrane potential and then eventually restore it to its resting potential state. It has two phases, a ________________ phase followed by a ________________phase.
Action.
Depolarization.
Repolarization.
During the depolarization phase of an action potential the first channels that open are the voltage –gated ______ ion channels, allowing _____ ions to rush into the neuron cytosol leading to depolarization.
Na+
K+
A subthreshold stimulus will not cause an action potential but a suprathreshold stimulus leads to what occurrence?
Depolarization of the Membrane above Threshold.
A light touch of the finger to a surface generates (more or fewer) action potentials compared to a firm touch although each action potential is of the same amplitude (strength).
Fewer.
